A respirator (ventilator) for medical applications has become known from U.S. Pat. No. 4,323,064. An inspiration tube and an expiration tube are connected to one another via a Y-piece, with a flow sensor and a respiration tube being connected to the end of the Y-piece pointing toward the patient. The flow sensor detects the gas flow both during the inspiration phase and during the expiration phase. The electric contacting of the flow sensor is achieved via a cable connection, which extends from the respirator to the flow sensor.
The drawback of the prior-art respirator is that the cable connection must be led separately to the evaluating device from the breathing gas tubes. If other parameters of the gas, such as the breathing gas temperature, the O2 or CO2 concentration, are also measured, besides the gas flow, additional cable connections are necessary, which compromise care procedures performed at the patient due to the sensors being arranged close to the patient.
EP 201 985 A1 discloses a breathing gas tube, which has a resistance wire extending helically along the tube. A sensor wire, which is used for contacting temperature sensors, which are arranged at the ends of the breathing gas tube, is led in parallel to the resistance wire.
The drawback of the prior-art breathing gas tube is that sensors which are located at adjacent connectors connected to the breathing gas tube must be connected to the sensors via separate electric patch plugs. Since breathing gas tubes are regularly sterilized or disinfected in clinical practice, such patch plugs are subject to high wear and, moreover, contact resistances may develop at the contact points, and these resistances may distort the often very low measured signal voltages. In addition, the number of plugging cycles is limited in electric patch plugs, so that the entire breathing gas tube must be replaced after a certain duration of use because of contacts that have become unfit for use.